Ground clutch assembly with dynamic engagement and disengagement

Abstract

Conversion of a vehicle between two-wheel drive and four-wheel drive is effected by means of a camming assembly and a shift mechanism to temporarily lock the camming assembly against rotation in advancing a drive gear into driving engagement with a receiving gear in converting to four-wheel drive, or to re-engage the camming assembly under the control of the shift mechanism as a preliminary to disengaging the drive gear from the receiving gear in converting to two-wheel drive.

We claim: 
     
       1. A clutch assembly for converting a vehicle between two-wheel drive and four-wheel drive by effecting dynamic engagement and disengagement between a drive shaft and a ground engaging wheel to be driven and wherein torque applying means are provided to selectively and positively rotate the drive shaft, said clutch assembly comprising; a fixed locking member;   a receiver gear drivingly connected to said wheel to be driven;   a drive gear keyed for rotation with said drive shaft and being axially movable with respect to said drive shaft, said drive gear interposed between said fixed locking member and the wheel to be driven and cam follower means associated with said drive gear;   an axially movable camming assembly provided with a cam surface, said cam follower means along with cam surface to impart axial movement to said drive gear along said drive shaft when said camming assembly is fixed against rotation and said drive gear is being rotated by said drive shaft; and   shift means movable into engagement with said fixed locking member whereby to temporarily lock said camming assembly against rotation, said cam follower means being responsive to positive rotation of said drive shaft when said camming assembly is locked against rotation by said fixed locking member to advance between first and second portions of said cam surface whereby said drive gear is advanced in an axial direction into and out of engagement with said receiving gear and said shift means and camming assembly are released from locking engagement with said fixed locking member so that said shift means and camming assembly are thereafter rotatable with said drive gear, and activating means for moving said shift means into engagement with said locking member independently of the application of torque to said drive shaft or the rotation of said wheel to be driven.   
     
     
       2. A clutch assembly according to claim 1, said activating means operative to cause said shift means to advance said camming assembly into locking engagement with said fixed locking member when said drive gear is drivingly connected to said receiving gear whereby continued rotation of said drive gear causes said drive gear to be separated from said receiving gear when said cam follower means traverses said first portion of said cam surface. 
     
     
       3. A clutch assembly according to claim 2, said drive gear operative to shift said camming assembly away from engagement with said fixed locking member after said drive gear is separated from said receiving gear and said cam follower means traverses said first portion of said cam surface. 
     
     
       4. A clutch assembly according to claim 1, wherein said vehicle includes a fixed housing disposed in outer spaced concentric relation to said drive shaft and terminating in axially spaced relation to said wheel member to be driven, said fixed locking member having inner and outer concentric sleeves with said inner concentric sleeve mounted in fixed relation to said spindle housing, and detent means interposed between the said inner and outer concentric sleeves operative to fix said outer concentric sleeve against rotation with respect to said inner concentric sleeve up to a predetermined force level, said outer concentric sleeve being free to rotate with respect to said inner concentric sleeve when the force of said shift means exceeds said predetermined force level. 
     
     
       5. A clutch assembly according to claim 4, said shift means having axially directed extension legs shiftable into engagement with locking elements on said outer concentric sleeve. 
     
     
       6. A clutch assembly according to claim 5, said camming assembly and said outer concentric sleeve of said fixed locking member having complementary locking elements movable into engagement with one another in response to activation of said shift means. 
     
     
       7. A clutch assembly according to claim 1, said camming assembly having said first cam surface portion engageable by said cam follower means to advance said drive grear axially into engagement with said receiving gear, said second cam surface portion engageable by said cam follower means to release said camming assembly from said fixed locking member for rotation with said drive gear upon engagement between said drive gear and said receiving gear, and a third cam surface portion engageable by said cam follower means to release said shift means from engagement with said locking member. 
     
     
       8. A clutch assembly according to claim 7, said camming assembly movable between a locking and release position with respect to said locking member irrespective of reversal in direction of rotation of said drive shaft. 
     
     
       9. A clutch assembly according to claim 7, said drive gear having said cam follower in the form of an outwardly projecting lug engagable with said cam surface portions. 
     
     
       10. A ground clutch assembly for converting a vehicle between two-wheel drive and four-wheel drive by effecting dynamic engagment and disengagement between a drive shaft and a ground-engaging wheel to be driven and wherein torque applying means are provided to selectively and positively rotates the drive shaft, said clutch assembly comprising: a fixed locking member in outer concentric relation to said drive shaft and in axially spaced relation to said wheel to be driven;   a receiver gear drivingly connected to said wheel to be driven, said receiver gear disposed in outer concentric relation to said drive shaft between said fixed locking member and said wheel to be driven;   a drive gear keyed for rotation with said drive shaft and being axially movable with respect to said drive shaft, said drive gear being interposed between said fixed locking member and the wheel to be driven, and said drive gear provided with cam follower means thereon;   an axially movable camming assembly disposed in outer concentric relation to said drive gear and provided with a cam surface engagable by said cam follower means to impart axial movement to said drive gear along said dirve shaft when said camming assembly is fixed against rotation and said drive gear is rotated by said drive shaft; and   shift means associated with said camming assembly and movable into engagement with said fixed locking member independently of the rotation of said drive gear or receiving gear, said cam follower means responsive to positive rotation of said drive shaft in either direction when said shift means is locked against rotation to successively (i) advance said camming assembly into direct engagement with said fixed locking member, (ii) advance said drive gear into engagement with said receiving gear and (iii) release said shift means and said camming assembly from locking engagement with said fixed locking member whereby said dirve gear and receiving gear are rotatable independently of said fixed locking member.   
     
     
       11. A ground clutch assembly according to claim 10, including activating means for selectively advancing said shift means and said camming assembly into locking engagement with said fixed locking member when said drive gear is drivingly connected to said receiving gear whereby continued rotation of said drive gear with said drive shaft causes said drive gear to be separated from said receiving gear in traversing said one portion of said cam surface. 
     
     
       12. A ground clutch assembly according to claim 10, said camming assembly defined by a plurality of concentric sleeves including a first sleeve having a first cam surface thereon facing in a direction away from said fixed locking member, a second sleeve having a second cam surface portion thereon facing in a direction toward said fixed locking member, and a third sleeve having a third cam surface portion thereon facing in a direction toward said fixed locking member. 
     
     
       13. A ground clutch assembly according to claim 12, said first, second and third cam surface portions defining a channel therebetween for movement of said cam follower in a generally circumferential direction. 
     
     
       14. A ground clutch assembly according to claim 12, said one cam surface portion operative to advance said drive gear axially into engagement with said receiving gear, said other cam surface portion engageable by said drive gear to release said camming assembly from said fixed locking member for rotation with said drive gear upon engagement between said drive gear and said receiving gear, and a third cam surface portion engageable by said drive gear to return said shift means to a neutral position. 
     
     
       15. A ground clutch assembly according to claim 14, said camming assembly movable between a locking and release position irrespective of reversal in direction of rotation of said drive shaft. 
     
     
       16. A ground clutch assembly according to claim 14, said followers defined by a pair of diametrically opposed, outwardly projecting lugs engagable with said cam surface portions. 
     
     
       17. A ground clutch assembly according to claim 10, wherein said vehicle includes a housing in outer spaced concentric relation to said drive shaft and terminating in axially spaced relation to said wheel member to be driven, said fixed locking member having inner and outer concentric sleeves with said inner concentric sleeve mounted in fixed relation to said spindle housing, and detent means interposed between the said inner and outer concentric sleeves operative to fix said outer concentric sleeve against rotation with respect to said inner concentric sleeve up to a predetermined force level, said outer concentric sleeve rotatable with respect to said inner concentric sleeve when the torque applied by said shift means exceeds said predetermined force level. 
     
     
       18. A ground clutch assembly according to claim 17, said shift means having axially directed extension legs shiftable into engagement with locking elements on said outer concentric sleeve. 
     
     
       19. A ground clutch assembly according to claim 18, said camming assembly and said outer concentric sleeve of said fixed locking member having complementary locking elements movable into engagement with one another in response to activation of said shifting means and relative rotation between said drive gear and said camming assembly. 
     
     
       20. In a clutch assembly for converting a vehicle between two-wheel drive and four-wheel drive by effecting positive engagement and disengagement between a drive shaft and a ground-engaging wheel to be driven, there being a receiver gear drivingly connected to the gound-engaging wheel and a drive gear keyed for rotation with said drive shaft but axially movable with respect to said drive shaft and provided with a cam follower thereon, the combination therewith comprising: an axially movable camming assembly in outer concentric relation to said drive gear having a circumferentially continuous camming channel defining a confined passageway in which said cam follower is constrained to move;   a fixed locking member in outer concentric relation to said drive shaft and in axially spaced relation to said gound-engaging wheel, said camming assembly having axially directed locking elements movable into engagement with said fixed locking member; and   shiftable interrupt means movable into engagement with said fixed locking locking member to initiate movement of said camming assembly into engagement with said locking member independently of engagement and disengagement between said drive gear and said receiver gear.   
     
     
       21. In a clutch assembly according to claim 20, including activating means for selectively activating said shiftable interrupt means in response to an electrical signal, said shiftable interrupt means movable out of engagement with said locking member upon movement of said camming assembly into engagement with said locking member. 
     
     
       22. In a clutch assembly according to claim 21, said activating means including a solenoid, an electrical power source and control circuit means to activate said solenoids in response to an electrical signal applied thereto. 
     
     
       23. In a clutch assembly according to claim 22 said control circuit means including a receiving antenna and a signal transmitting circuit including a signalling antenna for directing a remote control signal to said receiving antenna for energizing said activating means. 
     
     
       24. In a clutch assembly according to claim 23, said cam follower operative to retract said shiftable interrupt means from engagement said fixed locking member independently of said camming assembly. 
     
     
       25. In a clutch assembly according to claim 21, wherein said camming assembly is normally rotatable with respect to said fixed locking member, said camming assembly including a cam release portion said shiftable interrupt means being movable into engagement with said fixed locking member to prevent rotation of said camming assembly with respect to said locking member until the independent movement of said cam follower along said camming channel forces said locking elements on said camming assembly into locking engagement with said fixed locking member, the continued advancement of said cam follower along said camming channel and said fixed locking member until said drive gear is advanced axially into engagement with said receiving gear, further continued rotation of said cam follower along said camming channel after engagement between said drive gear and recieving gear causing said cam follower to move into engagement with said cam release portion causing said camming assembly to be disengaged from said fixed locking member.